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I p UNITED STATE "PA Y I EQ oTro iv. WITT, on WESTEND, 'NEAR'B R IN, AssieNoR TouunzsADrsoHE ANILIN AND SODA FABRIK, 'OFTMANNHEIM, GERMANY. A

MANUFACTURE OF PURPLE-BLACK A zo DYE-STUFF,

' SPECIFICATION forming part of Letters Patent No. 381,045, dated. April 10,1888. Application filed January 28,1888. Serial No. 2612,2661 (Specimens.)

.To: aZZ whom it may concern.-

. Be it known that I, OTTo N.W1TT, doctor of philosophy, a citizenof Switzerland, residing at Westend, near Berlin i'n the Kingdom 5 of Prussia and Empire of Germany, have invented new and useful Improvementsin the Manufacture of'a Purple vColoring-Matter or 'Dye-Stufflot which the following is a specification.

- This invention relates to the manufacture of a purple coloring-matter or dye-stuff of the class commonly known as azo dye-stuffs.

f To carry out myinvention I proceed as fo1- lows: I take 18.5parts, by weight, of binitro its diazo derivative by using any or either.

of the well-known methods for the purpose. As an example, I describe the following method (without, however, limiting myself'to its exclusive use.) I introducethe beforenamed quantity of binitro-aniline into one hundred parts, by weight, of ordinary concentrated or rectified sulphuric acid, in which previously either 6.9 parts, byweight, of sodic nitrite, or 3.8 parts, by weight, of nitrous anhydride have been dissolved. When allthe binitro-aniline has been taken up and dissolved by the acid,'I pour the solution thus obtained. upon chopped ice, and in this mannerI prepa'rean aqueous solution of .binitro-diazo-benzine sulphate. On the-other hand, I dissolve 265 parts, by weight, of beta-naphthylamine mono'sulphonateof sodium, of the modification'com monl y known as Brdnners, together with one hundred and sixty-five parts, by weight, of sodic acetate (taken as dry) in about one thousand parts of water; To this solution I add, in the cold, the solution of binitro-diazq' benzine sulphate, prepared as above described, stirring the liquid vigorously while the mix ture takes place. f I

The dye-stuff is formed at once and settles outin the shape of a dark-purple precipitate,

' which may be collected and purified by being redissolved in hot water and precipitated from aniline of themodification known to chemists this solution by the additionof salt vgater.

The dye-stuffqthus obtained forms in itsdry ostate a black powder, which'dissolves readily v in boiling water'with a deep-purple color. Thissolution remains liquid on cooling-,if the dye-stuff be quite pure. If, however, even "a small quantity of an alkali be present, these ,7

lution solidifies into a gelatinous I mass -of brownish-red color, which becomes liquid and purple on renewedheating. Acidsol'utions ofithe dye-stuff do not gelatinize on cooling.

Concentrated sulphuric acid dissolves my new dye-stuff with a dark-orange'color'. 1 5 Hot and I concentrated hydrochloric acid acts in the same manner. .On cooling, the free az'o acid a settles out-in theshape of'orangefiakes.

"In the above process the sodic beta-naphthylamine monosulphonate (Bronners-modifica tion) may be replaced'partly'" or wholly bythe sodium salt of the so-called delta-mono sul- I phonic acid of beta-naphthylamine without materially altering theresult obtained;- If, how

ever, any of the other isomeric beta-naphthylamine sulphonates known-"at thepresen't time be used, then the result'is 'no longer the same", dye-stufi's of a brownish shade being formed.

My'newdye-stuff dyes either wool or silk 7:

from an acidulated dye-bathin purple shades of considerable depthandbody;

Letters Patent, is

The purple azo scribed, which forms in a dry state aT-black powder and dissolves readily in boiling water, forming a solution of a deep purple color,

which remains liquid0n-"cooli-ng,-if the dye- 'What Iclaim as new, and desireto secure by 1.

stuff be quite pure; but if a small quantity-M83 an alkali be present said solution oncooling solidifies'into a gelatinous mass of. brownish--' red color, which-becomes liquid and purple on renewed heating.

' In testimonywhereof-I' have hereuntoset my 0 7 hand in the presence of two subscribing wit dyestuft' hereinbefore dev 

